The present invention relates to a method for manufacturing tea by treating the leaves of cyclobalanopsis stenophylla (Fagaceae), also known as Quercus salicina.
The cyclobalanopsis stenophylla is an evergreen tree which belongs to Fagaceae. Its leaves are elliptical, somewhat long and cuspidated. The edge of the leaf is saw-toothed. The veins in the center of the leaf, and the back thereof is white as if there is a layer of powder thereon.
It is known that cyclobalanopsis stenophylla when taken as a folk remedy and after it has been decocted, dissolves a calculus such as a biliary calculus or a renal calculus and discharges it from the body. In 1958, its medical benefits as a litholysis agent were experimentally proved for the first time at a medical school of a Japanese University (Tokushima University). In 1966, its medical benefits were again proved effective as a result of an experiment conducted by the Tokyo University.
It is generally known that flavonoid (quercetin, kaempferol, isoquercitrin), tannin (ellagic acid 3, 3'-di-o-methylellagic acid, .beta.-D-glucongallin, catechol, pyrogallol, gallic acid), fatty acid (succinic acid), threeterpene (fridelin, friedelanol, epifriedelanol) are constituent parts of the cyclobalanopsis stenophylla leaf.
It has been shown that a 10% sinking solution of the cyclobalanopsis stenophylla leaf dissolved 50% to 90% of a calculus comprised of cholesterol and stearic acid. Although it was stated that such dissolution was by catechol tannin, the accurate mechanism of dissolving a calculus is still the object of scientific study which must be revealed because other fatty acids are present in addition to tannin.
It has also been revealed by a clinical demonstration and an animal experiment that the sinking solution of the cyclobalanopsis stenophylla leaf was stable as a folk medicine because it produced no effect on bile secretion, breathing and blood pressure. The essence extracted by boiling the leaves of cyclobalanopsis stenophylla is used as tea. Also, tea made from an extract of its leaf has been placed on the market.